Water securityThe Answer to Groundwater Resources Comes from High in the Sky
Groundwater makes up 30 to 50 percent of California’s water supply, but until recently there were few restrictions placed on its retrieval. Then in 2014 California became the last Western state to require regulation of its groundwater, and water managers in the state’s premier agricultural region – the state’s Central Valley – are tasked with estimating available groundwater. It’s a daunting technological challenge – but scientists can help by pairing satellite data with high-resolution monitoring to estimate groundwater depletion.
Groundwater makes up 30 to 50 percent of California’s water supply, but until recently there were few restrictions placed on its retrieval. Then in 2014 California became the last Western state to require regulation of its groundwater. With deadlines starting this year, for the first time water managers in the nation’s premier agricultural region – the state’s Central Valley – are tasked with estimating available groundwater. It’s a daunting technological challenge.
Now a new computational approach developed by scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) offers a high-tech yet simple method: it pairs high-resolution images derived by satellite with advanced computer modeling to estimate aquifer volume change from observed ground deformation. The method could help streamline groundwater tracking across a region, once multiple local management agencies begin submitting water management plans to comply with the 2014 Sustainable Groundwater Management Act (or SGMA, pronounced “sigma).
“Drought has been prevalent throughout California’s history and is inevitable in the future. The traditional methods for measuring groundwater levels have limitations for the type of integrated management required under SGMA,” said Peter Nico, a Berkeley Lab environmental geochemist, and researcher involved in the effort. “Using this technique, it’s possible to create a ‘living’ model of groundwater resources for the Central Valley that could be updated frequently and used at either a very local scale or a very large scale.”
Berkeley says that the method applies one of Berkeley Lab’s key strengths – computing – to an area that is a significant point of focus for the Lab: water sustainability. The scientists believe it could lay the framework needed for water managers to portray Central Valley groundwater resources at a small, local scale and also at a broader scale that takes into account aggregated resources from various nearby jurisdictions.
What Land Deformation Says about Aquifer Volume
In this project, the scientists leveraged data obtained from Synthetic Aperture Radar (SAR) satellites representing observed surface subsidence, or where land is sinking and groundwater storage capacity has shrunk. Such data provides a far more detailed and macro-level snapshot of aquifer compaction, a process that is sensitive to groundwater levels across the Central Valley. They paired the satellite observations with a public database of wells drilled in California in order to estimate the spatial distribution of the aquifer volume that is lost each month in the state due to pumping.
